This observation raises questions about certain conclusions that have been drawn using causal models in quantum foundations. For example, the fact that any causal model which reproduces the Bell correlations must be fine-tuned is sometimes taken to mean that there is some mystery about the Bell correlations which urgently requires explanation[1]}, but the line of reasoning we have pursued here tells us that it's not surprising that we are unable to find a satisfying causal model for the Bell correlations, because the Bell correlations are simply not the right kind of thing to analyse with a causal model. Note that this is true even though the Bell correlations can be described in interventionist terms, with the preparation and measurements playing the role of the `loci of possible interventions' - an interventionist analysis can succeed in transforming a bi-order into a directed acyclic graph only if there is some well-defined bi-order present, so in the case of the Bell correlations, since these processes need not instantiate causal order, there is no reason to expect that an interventionist analysis will yield a sensible causal model. Of course, results like that of Wood and Spekkens are still very important to help us understand the specific ways in which standard causal models fail in the context of quantum mechanics, but the point is that we should not be too distressed to find that no non-fine-tuned causal model is possible for these phenomena.
